Arizona Garden: Sissoo, Pindo palm, carob trees

Question: We have several sissoo trees in our community, planted about a year ago, and now our present board says they must be removed promptly because of the danger the roots present. We have read pros and cons and don't understand this -- they have provided good shade already and are healthy. Any thoughts?

Answer: Dalbergia sissoo, or Indian rosewood as it is also called, is a semi-deciduous tree from India. Sissoo trees are being planted here in the lower deserts for shade. I think the nightmare stories that are being shared are mainly due to "wrong plant, wrong location." This tree is very tolerant of our extremes in the lower desert.

I would suggest not planting it near a patio or sidewalk. The roots are able to travel quite a distance to water (hence its survival technique). Phoenix is a city that needs all the shade we can give it. If the trees are not in an area where the possibility exists of a patio or sidewalk being destroyed, I would say keep the trees. Do some more research, and go look at existing sissoo trees in similar situations as yours and make a truly informed decision.

Q: I planted a 15-gallon Pindo palm in place of one of my failed queens. It has been in the ground for approximately six months. It is growing slowly, producing new leaves. However, the older leaves have dark brown spots on them, and as they age, these spots become almost solid on the center stalk. These older leaves are not dead -- but they look as if they have some sort of disease. I do not see any insects anywhere on the plant. Other than these dark spots, it looks healthy. Is this natural for this palm, or do I have a problem?

A: It sounds like your Pindo palm is actually OK. As long as the new leaves are green and healthy-looking, I think the spots on the old leaves and leaf stalks (or petioles) are normal.

You had mentioned your palms were only in the ground for six months. I think they are probably going through some planting shock. I would suggest, however, not to water overhead. You might be creating a situation for leaf spot or fungus. Pindo palm, or Butia capitata, is truly a desert-adapted palm that does well in our soil and can tolerate our heat. I've noticed that after planting some of the older leaves on my Pindos look spotted as well. Don't be tempted to remove all the spotted leaves. The plant needs them to protect the core, especially the first couple of years. Water deeply twice a week and fertilize with fish emulsion as directed.

Q: I purchased a carob tree from my local nursery in a 15-gallon container in January or February of this year. The nursery also planted the tree. The tree is in full sun and is getting lots of new growth. The problem: A lot of the leaves turn partially black, then turn brown and then fall off, but new growth continues. I believe the tree might be a miniature. The end 2 inches of all the branches are now bare. Any suggestions?

A: You mentioned that the carob tree is getting lots of new growth, but you also say its top or end growth is turning black then brown and falling off, and the top 2 inches are bare. I'm confused. I would, however, suggest that you deep-soak your new tree three times per week, for about 20 minutes each cycle. Do not water the new tree from above or by spraying it. You mentioned that it was turning black first. This sounds like it could have wet feet. Did you make sure it was well drained? I also do not recommend any fertilizer the first year.

Q: I recently read with great interest your recent article in The Republic about pruning palms. We have four beautiful 40-foot palms that we prune once every year after the seeds show up. My question is this: How can our pruner climb the trees without using the climbing spikes? He can reach only about one-third the way up on his extension ladder.

A: I found out recently that there are different types of climbing spikes. One kind does little to no damage because it doesn't penetrate too far into the tree's outer bark. The other, which is longer and more daggerlike, does. I hope this helps.

Q: I have four trumpet vines that have grown to about 15 feet high. The roots have gone under the brick work I have around them and are breaking the brick apart. Can I cut these roots and trim the bushes (vines) to about 7 feet with out killing the plants? If so, when is the best time of the year to do it?

A: The answer is yes, you can trim your trumpet vines back 50 percent. I would caution you to do this in the late fall once the foliage has diminished and you can see the structure. I do not think this will solve your root/brick problem, however.

Q: I have a Bishop's cap and a red barrel cactus. Both are more than 20 years old. Both are leaning toward the east. The leaning looks severe, and I am wondering if I should I give them a brace?

A: I spoke with Scott McMahon, our cacti collections manager, and he had this to share: "If you are very careful, you can dig around and remove soil from the base of each plant and resettle the cacti into a more upright position, then brace them with a support rock to stabilize them. Consider moving them to an area with filtered light that is more even from east to west." This does happen to many cactuses that are reaching to light.

Kissinger is director of horticulture at the Desert Botanical Garden. E-mail your garden questions to bkissinger@dbg.org.

A sissoo tree provides shade, which is needed by commuters waiting for the bus at this park-and-ride lot in Gilbert. However, due to its long root reach, a sissoo should typically not be planted near a sidewalk.